/Engine/Source/Runtime/Engine/Public/Animation/SkeletonRemapping.h
Get the specified additive rotation retargeted from the source skeleton onto the target skeleton, corrected for differences between source and target rest poses
Rotation mapped onto the target skeleton
FQuat RetargetAdditiveRotationToTargetSkeleton ( int32 TargetSkeletonBoneIndex, const FQuat & SourceRotation ) const